In recent years, semiconductor memory devices have been used for a variety of electronic devices. Semiconductor memory devices are classified into volatile memories in which stored data is lost when the power is turned off and nonvolatile memories in which stored data is held even when the power is turned off. These memories are used separately depending on the kind and usage of data.
Among the memories, memories each having a plurality of memory cells which are writable only once, which are one kind of nonvolatile memories, are preferable from a security viewpoint because tampering with data is not easily performed. Note that the memories are referred to as one time programmable memories (hereinafter referred to as OTP memories) or the like.
As one kind of OTP memories, an anti-fuse memory has been proposed in which one of electrodes is formed using metal and an anti-fuse is brought into conduction by reacting amorphous silicon with the metal so as to be silicide (for example, see Reference 1).
In addition, a circuit has been proposed in which a capacitor for compensating electric power in writing (hereinafter referred to as an assist capacitor) is provided in parallel with an OTP memory element (for example, see Reference 2). In particular, in an OTP memory in which silicide reaction occurs in writing, high yield can be realized by providing an assist capacitor.